Hi Vincent, I have a small request on this patch, which is useful for [1]. I'll detail what is needed lower in the code. [1] https://lore.kernel.org/lkml/ZWYDr6JJJzBvsqf0@xxxxxxx/ On Thursday 09 Nov 2023 at 11:14:32 (+0100), Vincent Guittot wrote: > Create a new method to get a unique and fixed max frequency. Currently > cpuinfo.max_freq or the highest (or last) state of performance domain are > used as the max frequency when computing the frequency for a level of > utilization but: > - cpuinfo_max_freq can change at runtime. boost is one example of > such change. > - cpuinfo.max_freq and last item of the PD can be different leading to > different results between cpufreq and energy model. > > We need to save the reference frequency that has been used when computing > the CPUs capacity and use this fixed and coherent value to convert between > frequency and CPU's capacity. > > In fact, we already save the frequency that has been used when computing > the capacity of each CPU. We extend the precision to save kHz instead of > MHz currently and we modify the type to be aligned with other variables > used when converting frequency to capacity and the other way. > > Signed-off-by: Vincent Guittot <vincent.guittot@xxxxxxxxxx> > Reviewed-by: Lukasz Luba <lukasz.luba@xxxxxxx> > Tested-by: Lukasz Luba <lukasz.luba@xxxxxxx> > Acked-by: Sudeep Holla <sudeep.holla@xxxxxxx> > --- > arch/arm/include/asm/topology.h | 1 + > arch/arm64/include/asm/topology.h | 1 + > arch/riscv/include/asm/topology.h | 1 + > drivers/base/arch_topology.c | 29 ++++++++++++++--------------- > include/linux/arch_topology.h | 7 +++++++ > include/linux/sched/topology.h | 8 ++++++++ > 6 files changed, 32 insertions(+), 15 deletions(-) > > diff --git a/arch/arm/include/asm/topology.h b/arch/arm/include/asm/topology.h > index c7d2510e5a78..853c4f81ba4a 100644 > --- a/arch/arm/include/asm/topology.h > +++ b/arch/arm/include/asm/topology.h > @@ -13,6 +13,7 @@ > #define arch_set_freq_scale topology_set_freq_scale > #define arch_scale_freq_capacity topology_get_freq_scale > #define arch_scale_freq_invariant topology_scale_freq_invariant > +#define arch_scale_freq_ref topology_get_freq_ref > #endif > > /* Replace task scheduler's default cpu-invariant accounting */ > diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h > index 9fab663dd2de..a323b109b9c4 100644 > --- a/arch/arm64/include/asm/topology.h > +++ b/arch/arm64/include/asm/topology.h > @@ -23,6 +23,7 @@ void update_freq_counters_refs(void); > #define arch_set_freq_scale topology_set_freq_scale > #define arch_scale_freq_capacity topology_get_freq_scale > #define arch_scale_freq_invariant topology_scale_freq_invariant > +#define arch_scale_freq_ref topology_get_freq_ref > > #ifdef CONFIG_ACPI_CPPC_LIB > #define arch_init_invariance_cppc topology_init_cpu_capacity_cppc > diff --git a/arch/riscv/include/asm/topology.h b/arch/riscv/include/asm/topology.h > index e316ab3b77f3..61183688bdd5 100644 > --- a/arch/riscv/include/asm/topology.h > +++ b/arch/riscv/include/asm/topology.h > @@ -9,6 +9,7 @@ > #define arch_set_freq_scale topology_set_freq_scale > #define arch_scale_freq_capacity topology_get_freq_scale > #define arch_scale_freq_invariant topology_scale_freq_invariant > +#define arch_scale_freq_ref topology_get_freq_ref > > /* Replace task scheduler's default cpu-invariant accounting */ > #define arch_scale_cpu_capacity topology_get_cpu_scale > diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c > index b741b5ba82bd..e8d1cdf1f761 100644 > --- a/drivers/base/arch_topology.c > +++ b/drivers/base/arch_topology.c > @@ -19,6 +19,7 @@ > #include <linux/init.h> > #include <linux/rcupdate.h> > #include <linux/sched.h> > +#include <linux/units.h> > > #define CREATE_TRACE_POINTS > #include <trace/events/thermal_pressure.h> > @@ -26,7 +27,8 @@ > static DEFINE_PER_CPU(struct scale_freq_data __rcu *, sft_data); > static struct cpumask scale_freq_counters_mask; > static bool scale_freq_invariant; > -static DEFINE_PER_CPU(u32, freq_factor) = 1; > +DEFINE_PER_CPU(unsigned long, capacity_freq_ref) = 1; It would be good for this to be initialized to 0 for other users that might want to detect when capacity_freq_ref was not yet set. > +EXPORT_PER_CPU_SYMBOL_GPL(capacity_freq_ref); > > static bool supports_scale_freq_counters(const struct cpumask *cpus) > { > @@ -170,9 +172,9 @@ DEFINE_PER_CPU(unsigned long, thermal_pressure); > * operating on stale data when hot-plug is used for some CPUs. The > * @capped_freq reflects the currently allowed max CPUs frequency due to > * thermal capping. It might be also a boost frequency value, which is bigger > - * than the internal 'freq_factor' max frequency. In such case the pressure > - * value should simply be removed, since this is an indication that there is > - * no thermal throttling. The @capped_freq must be provided in kHz. > + * than the internal 'capacity_freq_ref' max frequency. In such case the > + * pressure value should simply be removed, since this is an indication that > + * there is no thermal throttling. The @capped_freq must be provided in kHz. > */ > void topology_update_thermal_pressure(const struct cpumask *cpus, > unsigned long capped_freq) > @@ -183,10 +185,7 @@ void topology_update_thermal_pressure(const struct cpumask *cpus, > > cpu = cpumask_first(cpus); > max_capacity = arch_scale_cpu_capacity(cpu); > - max_freq = per_cpu(freq_factor, cpu); > - > - /* Convert to MHz scale which is used in 'freq_factor' */ > - capped_freq /= 1000; > + max_freq = arch_scale_freq_ref(cpu); > > /* > * Handle properly the boost frequencies, which should simply clean > @@ -279,13 +278,13 @@ void topology_normalize_cpu_scale(void) > > capacity_scale = 1; > for_each_possible_cpu(cpu) { > - capacity = raw_capacity[cpu] * per_cpu(freq_factor, cpu); > + capacity = raw_capacity[cpu] * per_cpu(capacity_freq_ref, cpu); The only affected code that I could find is here and below. The above line would have to change to: capacity = raw_capacity[cpu] * per_cpu(capacity_freq_ref, cpu) ?: 1; > capacity_scale = max(capacity, capacity_scale); > } > > pr_debug("cpu_capacity: capacity_scale=%llu\n", capacity_scale); > for_each_possible_cpu(cpu) { > - capacity = raw_capacity[cpu] * per_cpu(freq_factor, cpu); > + capacity = raw_capacity[cpu] * per_cpu(capacity_freq_ref, cpu); and here: capacity = raw_capacity[cpu] * per_cpu(capacity_freq_ref, cpu) ?: 1; I think it's nicer to start with capacity_freq_ref as 0 and compensate here for uninitialized capacity_freq_ref. Let me know if this is alright of if you'd prefer us to make this change in a separate patch. Thanks, Ionela. > capacity = div64_u64(capacity << SCHED_CAPACITY_SHIFT, > capacity_scale); > topology_set_cpu_scale(cpu, capacity); > @@ -321,15 +320,15 @@ bool __init topology_parse_cpu_capacity(struct device_node *cpu_node, int cpu) > cpu_node, raw_capacity[cpu]); > > /* > - * Update freq_factor for calculating early boot cpu capacities. > + * Update capacity_freq_ref for calculating early boot cpu capacities. > * For non-clk CPU DVFS mechanism, there's no way to get the > * frequency value now, assuming they are running at the same > - * frequency (by keeping the initial freq_factor value). > + * frequency (by keeping the initial capacity_freq_ref value). > */ > cpu_clk = of_clk_get(cpu_node, 0); > if (!PTR_ERR_OR_ZERO(cpu_clk)) { > - per_cpu(freq_factor, cpu) = > - clk_get_rate(cpu_clk) / 1000; > + per_cpu(capacity_freq_ref, cpu) = > + clk_get_rate(cpu_clk) / HZ_PER_KHZ; > clk_put(cpu_clk); > } > } else { > @@ -411,7 +410,7 @@ init_cpu_capacity_callback(struct notifier_block *nb, > cpumask_andnot(cpus_to_visit, cpus_to_visit, policy->related_cpus); > > for_each_cpu(cpu, policy->related_cpus) > - per_cpu(freq_factor, cpu) = policy->cpuinfo.max_freq / 1000; > + per_cpu(capacity_freq_ref, cpu) = policy->cpuinfo.max_freq; > > if (cpumask_empty(cpus_to_visit)) { > topology_normalize_cpu_scale(); > diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h > index a07b510e7dc5..32c24ff4f2a8 100644 > --- a/include/linux/arch_topology.h > +++ b/include/linux/arch_topology.h > @@ -27,6 +27,13 @@ static inline unsigned long topology_get_cpu_scale(int cpu) > > void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity); > > +DECLARE_PER_CPU(unsigned long, capacity_freq_ref); > + > +static inline unsigned long topology_get_freq_ref(int cpu) > +{ > + return per_cpu(capacity_freq_ref, cpu); > +} > + > DECLARE_PER_CPU(unsigned long, arch_freq_scale); > > static inline unsigned long topology_get_freq_scale(int cpu) > diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h > index de545ba85218..a6e04b4a21d7 100644 > --- a/include/linux/sched/topology.h > +++ b/include/linux/sched/topology.h > @@ -279,6 +279,14 @@ void arch_update_thermal_pressure(const struct cpumask *cpus, > { } > #endif > > +#ifndef arch_scale_freq_ref > +static __always_inline > +unsigned int arch_scale_freq_ref(int cpu) > +{ > + return 0; > +} > +#endif > + > static inline int task_node(const struct task_struct *p) > { > return cpu_to_node(task_cpu(p)); > -- > 2.34.1 >
